Context/desktop menu polish: real hover tint, real separator line, Select All

Reported live: "looks weird and unpolished... need a lot more items".
Compared directly against the exact AGS reference this project's own
menu rebuild already targets rather than guessing:

- Highlighted rows used a flat, fully-saturated fill instead of the
  reference's subtle 22%-accent-into-background wash. New decoration::
  color::mix_rgb (channel-wise linear blend, generalizing brighten/
  darken's fixed-target blends to an arbitrary second colour/ratio) lets
  render_context_menu reproduce that same ratio.
- Every separator row was a label string of Unicode box-drawing
  characters rendered as text glyphs, which render inconsistently at
  small sizes - a label that's entirely U+2500 now draws a real 1px
  hairline instead; a label that mixes it with real text ("--- Move to
  Workspace ---", a deliberate section-header convention) still renders
  as text, unchanged.
- "Select All" added to the bare-desktop menu, the one action every
  mainstream desktop's own menu offers that this one lacked.

New tests needed real care: the panel's own rounded-corner distance
field softens alpha within its radius of any canvas edge, not just the
visible corners, so a naive full-row pixel scan against bg picked that
up as a false positive on the first attempt - fixed by scanning only
rows/columns confirmed (via a throwaway debug dump) to sit inside the
panel's genuinely flat interior.

Full workspace build/test/clippy clean, built and installed. Real
submenus and per-row icons remain real, separate scope - this
project's floating-menu UI has no nested-panel concept yet.

1 files changed, 7 insertions, 1 deletions

diff --git a/crates/wayland/src/desktop_menu.rs b/crates/wayland/src/desktop_menu.rs
index 3cb90ed..dbbf957 100644
--- a/crates/wayland/src/desktop_menu.rs
+++ b/crates/wayland/src/desktop_menu.rs
@@ -30,6 +30,11 @@ pub(crate) enum DesktopMenuAction {
     /// concrete path to a real file manager's own richer menu (cut/copy/
     /// paste, properties, ...), deliberately not reimplemented here.
     OpenInFileManager,
+    /// Selects every desktop icon at once - the one bare-desktop menu
+    /// action every mainstream file manager/desktop offers (Explorer,
+    /// Nautilus, Finder) that this menu had no equivalent for at all,
+    /// reported live as this menu needing "a lot more items".
+    SelectAll,
     Refresh,
     /// A purely visual divider row - see `context_menu::MenuAction::
     /// Separator`'s own doc comment (same shape, same reason, separate
@@ -78,6 +83,7 @@ impl DesktopMenu {
             ("Open Terminal Here", DesktopMenuAction::OpenTerminalHere),
             ("Open in File Manager", DesktopMenuAction::OpenInFileManager),
             ("\u{2500}\u{2500}\u{2500}\u{2500}\u{2500}\u{2500}\u{2500}\u{2500}\u{2500}\u{2500}\u{2500}\u{2500}\u{2500}\u{2500}\u{2500}", DesktopMenuAction::Separator),
+            ("Select All", DesktopMenuAction::SelectAll),
             ("Refresh", DesktopMenuAction::Refresh),
         ];
         Self { pos, width: MENU_WIDTH, row_height: ROW_HEIGHT, items }
@@ -144,7 +150,7 @@ mod tests {
         let menu = DesktopMenu::open_for_desktop((10, 10));
         let real_actions: Vec<&str> =
             menu.items.iter().filter(|(_, a)| !matches!(a, DesktopMenuAction::Separator)).map(|(l, _)| *l).collect();
-        assert_eq!(real_actions, vec!["New Folder", "New Text Document", "Open Terminal Here", "Open in File Manager", "Refresh"]);
+        assert_eq!(real_actions, vec!["New Folder", "New Text Document", "Open Terminal Here", "Open in File Manager", "Select All", "Refresh"]);
     }
 
     #[test]